How to Implement a Property

Below is a code snippet of how we implement non-trivial properties, involving event subscriptions and change notifications (through INotifyPropertyChanged). Unsubscribing from the old value’s events is particularly important to avoid memory leaks.

public Amount BatchAmount
{
  set
  {
    // Do nothing if the value hasn't changed (certainly avoid change notification)
    if (batchAmount == value)
      return;

    // Unsubscribe from the old value's events (prevent memory leak)
    if (batchAmount != null)
      batchAmount.PropertyChanged -= batchAmount_PropertyChanged;

    // Assign the new value
    batchAmount = value ?? new Amount(0, UnitPrice.Unit);

    // Subscribe on the new value's events
    batchAmount.PropertyChanged += batchAmount_PropertyChanged;

    // Notify property changed
    OnPropertyChanged("BatchAmount");
  }
}